As part of our investigations dealing with the dolichol pathway of carbohydrate-activation in the retina, we are examining its role in the biosynthesis of the carbohydrate chains of rhodopsin. We are investigating the ability of unglycosylated rhodopsin to act as an acceptor of the oligosaccharide chain from glucosamine-labeled oligosaccharide-lipids synthesized by the retina. Unglycosylated rhodopsin has been synthesized by employing the antibiotic, tunicamycin, and purified by adsorption chromatography and isoelectric focusing. In addition to the biosynthesis of rhodopsin, its turnover is an integral aspect of the visual process. We are investigating the enzymatic degradation of rhodopsin by the pigment epithelium and are following its hydrolysis to glycopeptides by cell-free preparations of that tissue.